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Biomedical subjects

Xin Li

Publications and source records attributed to Xin Li.

At least 307 records · Page 17Linked to original sources
PubMed2003

[Typing for HLA-DR DNA by polymerase chain reaction with sequence-specific primers].

AIM: To type the HLA-DR DNA for renal transplantation by PCR with sequence specific primers (PCR-SSP). METHODS: According to nucleotide sequences of HLA-DR, 16 pairs of specific primers and a pair of positive control primers were designed and synthesized for PCR-SSP. Then HLA-DR sites of 52 donors and recipients for renal transplantation were typed by the PCR-SSP. RESULTS: All the samples were successfully typed by PCR-SSP with the synthesized primers. The results were available within 3 hours after sampling and the accuracy and reproducibility were 100%. CONCLUSION: Genotyping for HLA-DR sites by PCR-SSP with primers reported herein was a simple and accurate technique suitable for clinical application.

Adolescent↗
PubMed2003

[Comparative study of dissolved matter of glycyrrhizic acid before and after supermicro-pulverization of Radix Glycyrrhizae].

OBJECTIVE: To investigate various activities of dissolved matter of glycyrrhizic acid of Radix Glycyrrhizae and the powder by supermicro-pulverization. METHOD: The contents of glycyrrhizic acid in different samples were tested. RESULT: The dissolved matter of glycyrrhizic acid was greatly increased by supermicro-pulverization. The more time used for grinding, the smaller the size of the powder, and the easier the glycyrrhizic acid would be dissolved. CONCLUSION: Supermicro-pulverization is helpful to the dissolved matter of glycyrrhizic acid of Radix Glycyrrhizae, and the size of powder exerts great influence on dissolved matter of glycyrrhizic acid.

Drug Combinations↗
PubMed2002

[Comparison of cryopreservation methods of umbilical hematopoietic stem/progenitor cells].

OBJECTIVE: To compare the different effects of the programmable cell freezer and the -70 degrees C mechanical freezer in the preservation of the combilical cord blood and to study the effects of magnetic activated cell sorting on cell biologic characters. METHODS: After separating the nucleated cells from the umbilical blood by the density gradient separation method, we used cryoprotectant to protect the nucleated cells and preserve them by two methods; one was using the programmable cell freezer to cool the cells and finally putting them to the liquid nitrogen, and the other one was directly preserving the cells in a -70 degrees C mechanical freezer. The cells were thawed after a month and tested for the viability and clonogenic ability. Cell recovery, clonogenic capacity and clonogenic recovery by the two cryopreservation methods were compared. Meanwhile, the CD34+ cells were sorted by the method of magnetic cell sorting from the umbilical cord blood, and the cell purity and recovery after sorting were analyzed by the method of fluorescence-activated cell sorting. RESULTS: There were no significant differences between the two preserving methods in cell viability, cell recovery, clonogenic capacity, or colony recovery. The purity of the CD34+ cells was 88.3% and the recovery rate was 46.2% after the cell sorting. The cell viability and clonogenic capacity of the CD34+ cells were much higher than those of the CD34- cells. CONCLUSION: The umbilical cord blood can be efficiently preserved by the two methods and highly purified CD34+ cells could be obtained by using the method of magnetic cell sorting. The procedure of cell sorting doesn't affect the viability and clonogenic ability. The study provides some evidence for clinical application of preserving the umbilical cord blood and transplanting CD34+ cells.

Antigens, CD34↗
PubMed2002

To probe the origin of activation effect of carboxylic acid and (+)-NLE in tridentated titanium catalyst systems.

The activation effect of carboxylic acid and positive nonlinear effect ((+)-NLE) in tridentated titanium catalyst systems for hetero Diels-Alder reaction and aldol-type reactions has been first elucidated on the basis of X-ray crystal structural analysis of homochiral (pseudo-octahedral coordination geometry with C2 symmetry) and heterochiral (pseudo-octahedral coordination geometry with C1 symmetry) titanium complexes and the observation of their different reactivities with carboxylic acid additive.

Journal Article↗
PubMed2002

Construction and selection of bead-bound combinatorial oligonucleoside phosphorothioate and phosphorodithioate aptamer libraries designed for rapid PCR-based sequencing.

Chemically synthesized combinatorial libraries of unmodified or modified nucleic acids have not previously been used in methods to rapidly select oligonucleotides binding to target biomolecules such as proteins. Phosphorothioate oligonucleotides (S-ODNs) or phosphorodithioate oligonucleotides (S2-ODNs) with sulfurs replacing one or both of the non-bridging phosphate oxygens bind to proteins more tightly than unmodified oligonucleotides and have the potential to be used as diagnostic reagents and therapeutics. We have applied a split synthesis methodology to create one-bead one-S-ODN and one-bead one-S2-ODN libraries. Binding and selection of specific beads to the transcription factor NF-kappaB p50/p50 protein were demonstrated. Sequencing both the nucleic acid bases and the positions of any 3'-O-thioate/dithioate linkages was carried out by using a novel PCR-based identification tag of the selected beads. This approach allows us to rapidly and conveniently identify S-ODNs or S2-ODNs that bind to proteins.

Base Sequence↗
PubMed2002

Retinal pigment epithelial cells exhibit unique expression and localization of plasma membrane syntaxins which may contribute to their trafficking phenotype.

The SNARE membrane fusion machinery controls the fusion of transport vesicles with the apical and basolateral plasma-membrane domains of epithelial cells and is implicated in the specificity of polarized trafficking. To test the hypothesis that differential expression and localization of SNAREs may be a mechanism that contributes to cell-type-specific polarity of different proteins, we studied the expression and distribution of plasma-membrane SNAREs in the retinal pigment epithelium (RPE), an epithelium in which the targeting and steady-state polarity of several plasma membrane proteins differs from most other epithelia. We show here that retinal pigment epithelial cells both in vitro and in vivo differ significantly from MDCK cells and other epithelial cells in their complement of expressed t-SNAREs that are known - or suggested - to be involved in plasma membrane trafficking. Retinal pigment epithelial cells lack expression of the normally apical-specific syntaxin 3. Instead, they express syntaxins 1A and 1B, which are normally restricted to neurons and neuroendocrine cells, on their apical plasma membrane. The polarity of syntaxin 2 is reversed in retinal pigment epithelial cells, and it localizes to a narrow band on the lateral plasma membrane adjacent to the tight junctions. In addition, syntaxin 4 and the v-SNARE endobrevin/VAMP-8 localize to this sub-tight junctional domain, which suggests that this is a region of preferred vesicle exocytosis. Altogether, these data suggest that the unique polarity of many retinal pigment epithelial proteins results from differential expression and distribution of SNAREs at the plasma membrane. We propose that regulation of the expression and subcellular localization of plasma membrane SNAREs may be a general mechanism that contributes to the establishment of distinct sorting phenotypes among epithelial cell types.

Animals↗
PubMed2002

Screening and analysis of permeable compounds in Radix Angelica Sinensis with immobilized liposome chromatography.

Immobilized liposome chromatography (ILC) was used to screen and analyze permeable compounds in traditional Chinese medicines (TCMs), testing extracts from Radix Angelica Sinensis. More than 10 peaks were resolved based on their interactions with the ILC stationary phase, a system which mimics biomembranes; this means that more than 10 components in Radix Angelica Sinensis extract have significant retention on an ILC column. Two of them, ligustilide and ferulic acid, were identified from their MS spectrum and with standard samples. A possible molecular structure of another component retained on ILC was also preliminarily identified as 3-butylidene-4,5-dihydro-2(1,3H)-1-isobenzofuranol according to its MS spectrum, hydrophobicity and 1H NMR spectrum. Of all detected components, ligustilide had the best penetration ability through the biomembrane. The effects of pH, column temperature, and ionic strength on the chromatography of methanolic extracts of Radix Angelica Sinensis were also investigated. It was found that the separation selectivity on ILC is strongly affected by the eluent pH, but only slightly by the column temperature and ionic strength.

Angelica sinensis↗
PubMed2002

Reverse genetics by fast neutron mutagenesis in higher plants.

Fast neutron mutagenesis has long been used for forward genetic studies in plants. Only recently has it been used for reverse genetics. By combining fast neutron mutagenesis and high throughput PCR screening, a new knockout methodology, Deleteagene (Delete-a-gene), was developed in Arabidopsis and rice to obtain deletion mutants for target genes. Since fast neutron is a highly efficient mutagen that produces deletion mutations easily detectable by PCR, this method has the potential to enable reverse genetic screens in most plant species. In this review, we will discuss the use of fast neutron as a mutagen for creating deletion mutations, and strategies for successful application of Deleteagene in other plant species.

Arabidopsis↗
PubMed2002

Acid-free aza Diels-Alder reaction of Danishefsky's diene with imines.

[reaction: see text] A highly efficient aza Diels-Alder reaction of Danishefsky's diene with imines was found to occur in methanol in the absence of any acids at room temperature to give corresponding 2-substituted dihydro-4-pyridone derivatives in high yields. This reaction can be also carried out in a three-component one-pot reaction manner. The reaction was found to proceed through a Mannich-type condensation mechanism.

Journal Article↗
PubMed2002

HIPK2 associates with RanBPM.

Using the yeast two-hybrid system, we have identified the Ran-binding protein (RanBPM) as an interaction partner of homeodomain-interacting protein kinase 2 (HIPK2). RanBPM has been described as a centrosomal protein through which Ran regulates the centrosomal function. HIPK2 is mainly a nuclear protein, which among other functions represses transcription mediated by homeodomain containing transcription factors. Here, we show that overexpressed wildtype HIPK2 and a kinase defective mutant of HIPK2 directly interact with RanBPM in the nucleus of mammalian cells. Overexpressed wildtype RanBPM and a kinase defective mutant of HIPK2 co-localise with HIPK2 in defined nuclear structures. A carboxy- and an amino-terminal deletion of HIPK2 do not seem to be able to bind to RanBPM.

Adaptor Proteins, Signal Transducing↗
PubMed2002

Combinatorial selection and binding of phosphorothioate aptamers targeting human NF-kappa B RelA(p65) and p50.

Previously, we reported the in vitro combinatorial selection of phosphorothioate aptamers or "thioaptamers" targeting the transcription factor NF-IL6. Using the same approach and purified recombinant human NF-kappa B proteins RelA(p65) and p50, duplex thioaptamers have been selected that demonstrate high-affinity, competitive binding with the duplex 22-mer binding site, Ig kappa B. Binding energetics of RelA(p65) and p50 homodimers were studied using a quantitative electrophoretic mobility shift assay or EMSA. As a reference system for competitive aptamer binding, the duplex 22-mer phosphoryl binding site known as Ig kappa was determined to bind each p65 and p50 homodimer with a 1:1 stoichiometry and with affinities, determined by global analysis, K(d) = 4.8 +/- 0.2 nM for p65 and K(d) = 0.8 +/- 0.2 nM for p50. A global analysis tool for competitive NF-kappa B/Ig kappa binding was developed and utilized to measure the affinity of thioaptamers selected by both p65 and p50. The competition results indicate that the thioaptamers bind and compete for the same NF-kappa B site as the known promoter element Ig kappa B (K(d) = 78.9 +/- 1.9 nM for a p65-selected aptamer and 19.6 +/- 1.3 nM for a p50-selected thioaptamer). Qualitative gel shift binding experiments with p50 also demonstrate that the nature of enhanced affinity and specificity can be attributed to the presence of sulfur. Collectively, these results demonstrate the feasibility of the thioaptamer in vitro combinatorial selection technology as a method for producing specific, high-affinity ligands to proteins.

Base Sequence↗
PubMed2002

A double-blind, randomized, controlled trial of amphotericin B colloidal dispersion versus amphotericin B for treatment of invasive aspergillosis in immunocompromised patients.

We report a randomized, double-blind, multicenter trial in which amphotericin B colloidal dispersion (ABCD [Amphotec]; 6 mg/kg/day) was compared with amphotericin B (AmB; 1.0-1.5 mg/kg/day) for the treatment of invasive aspergillosis in 174 patients. For evaluable patients in the ABCD and AmB treatment groups, respective rates of therapeutic response (52% vs. 51%; P=1.0), mortality (36% vs. 45%; P=.4), and death due to fungal infection (32% vs. 26%; P=.7) were similar. Renal toxicity was lower (25% vs. 49%; P=.002) and the median time to onset of nephrotoxicity was longer (301 vs. 22 days; P<.001) in patients treated with ABCD. Rates of drug-related toxicity in patients receiving ABCD and AmB, respectively, were 53% versus 30% (chills), 27% versus 16% (fever), 1% versus 4% (hypoxia) and 22% versus 24% (toxicity requiring study drug discontinuation). ABCD appears to have equivalent efficacy and superior renal safety, compared with AmB, in the treatment of invasive aspergillosis. However, infusion-related chills and fever occurred more frequently in patients receiving ABCD than in those receiving AmB.

Adolescent↗
PubMed2002

[Clinical analysis of 9 cases of the normal-sized ovary carcinoma syndrome].

OBJECTIVE: To investigate clinical features, diagnostic criteria, treatment methods of a clinically rare "normal-sized ovary carcinoma syndrome". METHODS: Histologic slices of 9 cases of the normal-sized ovary carcinoma syndrome from 1990 to 1996 were retrospectively reviewed. Six of the 9 cases were extraovarian peritoneal serous papillary carcinoma(EPSPC). The other 3 cases were serous adenocarcinoma of the ovary (2 cases) and metastatic adenocarcinoma of unknown origin (1 case). All the patients received optimal cytoreductive surgery combined with multiple courses of effective adjuvant chemotherapy. RESULTS: Two patients with EPSPC survived for 84 months and 72 months respectively up to Dec., 1997. The average survival time of the 7 patients who died of their diseases was 16.5 months. CONCLUSION: For the normal-sized ovary carcinoma syndrome, surgical resection is the first choice of treatment, and postoperative chemotherapy is essential to obtain better prognosis.

Adenocarcinoma, Papillary↗
PubMed2002

[Effect of serum from patients with Graves' disease on colony forming unit-granulocyte monocyte].

OBJECTIVE: To investigate the effects of serum component from patients with Graves's disease (GD) on the growth of colony forming unit-granulocyte monocyte (GM-CFU). METHODS: Monocytes were obtained from 11 normal persons and 11 GD patients with leukopenia and culture together with sera from 11 GD patients with leukopenia, 11 GD patients without leukopenia, and 11 normal controls for 10 days. Inverted microscopy was used to count the number of colony. RESULTS: Thyroid stimulating immunoglobulin (TSI) and serum from GD patients with leukopenia significantly inhibited the formation of GM-CFU (P < 0.01) while methimazole, thyroxine and serum from GD patients without leukopenia did not have any effect on the formation of GFU-GM (P > 0.05). CONCLUSION: TSI and serum from GD patients with leukopenia remarkably inhibit GM-CFU growth. Autoimmune abnormality may play an important role in the pathogenesis of leukopenia in patients with GD.

Adult↗
PubMed2002

Proliferative marker Ki-67 in gallbladder carcinomas: high expression level predicts early recurrence after surgical resection.

To evaluate the prognostic value of proliferative maker Ki-67, its expression was determined immunohistochemically in 37 gallbladder carcinomas (GBCs). A high Ki-67 index was significantly correlated with tumor lymphatic invasion (P=0.007) and vascular invasion (P=0.04). High Ki-67 index group and low Ki-67 index group showed different clinical courses. Five patients who experienced recurrences in high Ki-67 index group developed their recurrent diseases within one year after surgery and died soon after recurrence, while the recurrences (five cases) in low Ki-67 index group were distributed all stages after surgery. In conclusion, high Ki-67 index predicts early recurrence after surgery for GBCs.

Aged↗
PubMed2002

Safety and efficacy of alteplase for restoring function in occluded central venous catheters: results of the cardiovascular thrombolytic to open occluded lines trial.

PURPOSE: To evaluate the safety and efficacy of alteplase (TPA) for restoring function to occluded central venous catheters (CVCs). PATIENTS AND METHODS: The study design was a phase III, open-label, single-arm multicenter trial. Subjects with occluded, nondialysis CVCs were enrolled. All subjects received a 2-mg dose of TPA within the dysfunctional catheter lumen that was allowed to dwell for 30 to 120 minutes. Functionality was tested at 30 and 120 minutes. If the CVC remained obstructed at 120 minutes, a second 2-mg TPA dose was allowed to dwell for 30 to 120 minutes. The primary safety end point was the rate of intracranial hemorrhage (ICH) within 5 days of treatment, and serious adverse events were recorded up to 30 days. RESULTS: Nine hundred ninety-five patients received treatment (female, 562; male, 433; mean age, 50.7 years; range, 2 to 91 years). CVCs treated were as follows: single (26%), double (39%), or triple (6%) lumen catheters or ports (29%). The primary end point was 0% ICH within 5 days. There were no cases of death, major bleeding episodes, or embolic events attributable to treatment. Flow was successfully restored in 52% and 78% of CVCs at 30 and 120 minutes after one dose, and 84% and 87% at 30 and 120 minutes after a second dose, respectively. Restoration of flow was 86%, 93%, 90%, and 79%, for single, double, and triple lumen catheters and ports, respectively. Estimated 30-day catheter patency was 74%. CONCLUSION: A regimen of up to two 2-mg doses of TPA is safe and effective for the restoration of flow to occluded central venous catheters.

Adolescent↗
PubMed2002

On the variability of covariate adjustment. experience with Koch's method for evaluating the absolute difference in proportions in randomized clinical trials.

Recently Koch et al. suggested an interesting approach for covariate adjustment in randomized clinical trials. Here we report our experience with the approach in Assent II, a large randomized trial comparing 30-day mortality rates of two thrombolytic treatments. Data from the Gusto-I study and a recent successor to the Assent II study will also be used. Further, we balance the advantage of covariate adjustment (with Koch's method) to the extra efforts and resources necessary. In this context we highlight the fact that there is a potential risk of using a covariate-adjusted analysis as primary analysis and show that covariate adjustment has the least effect when it is needed most. Analytic results will be given to quantify this risk and a simulation study illustrates our findings.

Data Interpretation, Statistical↗